Hitachi, Ltd.

Gosuke Okada

Mamoru Motonaga

Megumi Hokazono

Naoto Shiino

Takashi Yamazaki

Takashi Chikusa

Takashi Nozawa

Keiichiro Uchida

A storage apparatus and tier control method capable of executing hierarchical control based on variable performance of SSDs are suggested. With a storage apparatus equipped with a plurality of drives composed of flash memories, the storage apparatus includes a controller for hierarchically controlling storage areas provided by the plurality of drives by classifying the storage areas into a plurality of tiers with different performances and managing them, wherein the controller: decides a first tier, to which each of the drives should belong, based on performance of the drive; decides to change the tier, to which the drive should belong, from the first tier to a second tier different from the first tier based on the drive's performance, which varies depending on property of the drive; and changes the tier, to which the drive determined to change its tier should belong, from the first tier to the second tier.

Storage apparatus and tier control method

In storage subsystems, due to the significant increase in HDD capacity, the time for executing online verification is elongated, affecting accesses from the host computer. By comprehending the status of accesses to the HDD, the sections where error has occurred and the status of restoration thereof, it becomes possible to detect defective or error sections efficiently at an early stage, according to which the reliability and access performance of the storage subsystem can be improved. The present storage subsystem executes one or more of the following processes: (M1) intensive verification of a circumference of an error LBA, (M2) an area-based prioritized verification, and (M3) continuous verification performed for a long period of time to (V1) an area in which error has occurred via IO access, (V2) a highly accessed area, and (V3) during a period of time when IO access is low.

Storage subsystem and method for controlling the same

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Tokyo, Japan

Gosuke Okada